Human papillomavirus (HPV) is a common sexually-transmitted virus which causes infections that usually last only a few months, but sometimes can last a long time and cause cancers of the cervix, vagina, vulva, anus or oropharynx over many years among adults. This phase IIA trial studies how well does the nonavalent HPV vaccine (which can prevent nine different types of HPV) work when given in an alternative dosing schedule to heathy young research participants.

PRIMARY OBJECTIVES:

I. To determine the persistence and stability of serologic geometric mean titer (GMT) of HPV 16/18 between 6, 12, 18, and 24 months after the prime dose and prior to the administration of the second dose.

SECONDARY OBJECTIVES:

I. To determine the persistence and stability of serologic GMT of HPV types 6/11/31/33/45/52/58 between 6, 12, 18, and 24 months after prime dose and prior to the administration of the second dose.

II. To assess safety and reactogenicity to each vaccine dose.

OUTLINE:

Participants receive recombinant human papillomavirus nonavalent vaccine intramuscularly (IM) at baseline (priming injection) and at 24 and 30 months (booster injections).

After completion of study, participants are followed up for 2 weeks.

Inclusion Criteria:

• Healthy, medically well girls and boys
• Ability to understand and the willingness to sign a written informed consent document by the legal representative(s) of the participant
• Ability to understand and the willingness to sign a written assent document by the participant

Exclusion Criteria:

• Previous vaccination against HPV
• The use of any investigational agent within 30 days preceding the first dose of the study vaccine or subsequent participation in another clinical trial at any time during the study period, in which the subject will be exposed to an investigational product
• Chronic administration of immunosuppressive agents or other immune-modifying drugs or chemotherapeutic agents within six months prior to the first vaccine dose; use of inhaled steroids, nasal sprays, and topical creams for small body areas is allowed
• Receiving active treatment for cancer or an autoimmune condition
• Confirmed or suspected immunosuppressive or immunodeficient condition
• Known bleeding disorders that preclude intramuscular injection (e.g., on anticoagulants or thrombocytopenia)
• Acute or chronic, clinically significant pulmonary, cardiovascular, hepatic or renal dysfunction, which in the opinion of the investigator precludes administration of the study vaccine
• History of allergic reactions attributed to compounds of similar chemical or biologic composition of GARDASIL 9 (recombinant human papillomavirus nonavalent vaccine), including yeast allergy
• Are pregnant